Abstract: Photovoltaic power, also known as clean energy, is being widely connected to distribution network. However, a large number of grid-connected PV systems would change the direction of power flow. Besides, they affect the stability and safety of distribution network. Therefore, scientific estimate and simulation is necessary before Photovoltaic power's connecting to grid. Based on practical engineering requirement, different aspects of the typical bipolar photovoltaic power system has been researched to build the math models of different complexity. Finally, these models are simulated and analyzed in order to verify the correctness of different models in the situation of dynamic process. The major work of this thesis is as follows: (1)Different aspects of the typical bipolar photovoltaic power system has been researched, including photovoltaic cell model, chopper model, inverter model, filter model and the control model. Based on the integration of different models, the accurate transient-state-model is proposed. Due to the complexity of accurate model, fifth-order average model and third-order simplified model of typical photovoltaic power system are presented based on the method of average state. Finally, through Matlab, these models of different orders are simulated and analyzed in order to verify their correctness in the situation of voltage sag, change of light radiation and reactive power reference. (2)An example of PV cluster demonstration area has been researched to summarize the general characteristic of PV cluster. Based on photovoltaic power system model, further modeling and analysis of PV cluster has been researched. Due to the complexity of PV cluster model, a reduction method for the PV cluster model is proposed to reduce the orders of PV cluster model. Because PV cluster model can not estimate the effect of the voltage sag in PV cluster, the transient equivalent circuit of PV cluster is studied to compensate for the shortcomings of the PV cluster model. At the same time, the clustering equivalence model of PV cluster is proposed. The models of PV cluster are simulated by similar simulation situation to verify the simulation results of PV cluster in different practical environments and obtain the characteristic of PV cluster. (3)Finally, the characteristics of PV cluster model is been summarized. For the large and complex PV cluster, the Strategy of multi-model-switching simulation is put forward.